Technical Abstract:
This work attempts to characterize the precision of sample-blending procedures that have evolved over decades at the Southern Regional Research Center. Techniques for sampling and sample preparation are crucial to the reliability and validity of the results of any fiber-property testing method, especially those dealing with the measurement of fiber length. In order for the "laboratory sample" to be fully representative of the bulk source material and the "test specimen" to be optimized for meaningful test results, it is necessary to exert control over the sampling, blending, and specimen-preparation processes. This experiment was built around a 2 x 2 x 2 cross-treatment design, comprising two sample-blending methods (hand blending and mechanical blending) and two specimen-extraction techniques (multiple pinch vs. single tuft) applied to two fiber forms (raw lint and sliver). In each case, a 10-gram blended sample was prepared. Specimens of 0.5-grams each were withdrawn until the blended sample was exhausted. All specimens were analyzed by the AFIS length measurement system to measure the fiber length distribution. The experiment was replicated four times for each cotton tested. The entire length distribution by individual 1/16th-inch length interval was compared between samples and within samples (i.e., between specimens). Although the USDA blender technology was originally developed for the Suter-Webb Array Method, and was modified successfully for the Peyer Almeter System, it seems particularly adaptable to the newer AFIS length-measuring instruments. Variation in the measured short fiber content of raw cotton by AFIS was reduced by a factor of two through proper choice of sample-blending and specimen-compositing approaches.